Telon Mainframe Screens: Documenting 50-Step User Workflows

Your most critical business logic is currently trapped in a 3270 terminal emulator, protected by a developer who retired in 2014. For organizations running on CA Telon, the "green screen" isn’t just a UI—it’s a historical record of undocumented business rules, hidden validations, and complex screen-flows that have evolved over forty years. When you are tasked with telon mainframe screens documenting for a 50-step insurance claim or a cross-border wire transfer, you aren't just looking at a UI; you are looking at a forensic puzzle.

The reality of technical debt is staggering. With a $3.6 trillion global technical debt overhang, the pressure to modernize has never been higher. Yet, 70% of legacy rewrites fail or exceed their timelines because the tribal knowledge required to understand these workflows has evaporated. Manual documentation is no longer a viable strategy when an enterprise rewrite averages 18 months and costs millions in specialized labor.

TL;DR: Documenting 50-step workflows in Telon mainframes is traditionally a manual, error-prone process taking 40+ hours per screen. Replay changes this by using Visual Reverse Engineering to convert screen recordings into documented React components and structured workflows, reducing modernization timelines from years to weeks and saving 70% of the typical effort.

The Telon Trap: Why Manual Documentation Fails#

Telon was designed to accelerate mainframe development by generating COBOL or PL/I code from high-level definitions. While efficient in the 1980s, this abstraction layer now acts as a barrier. The source code generated by Telon is often verbose and difficult to map back to the actual user experience.

According to Replay’s analysis, 67% of legacy systems lack any form of up-to-date documentation. When a user navigates through a 50-step workflow, they are interacting with "Screen Definitions" and "BMS Maps" that hold implicit logic not found in the backend services.

Telon mainframe screens documenting becomes a bottleneck because:

1. •Field Macros: Telon uses macros to define screen attributes (color, protection, intensity) which are hard to parse visually without the original generator.
2. •Hidden Navigation: "Screen swapping" and "Transfer" logic are often buried in the generated COBOL, making it impossible to see the "happy path" of a user journey.
3. •State Persistence: In a 50-step flow, data is passed through the COMMAREA or TSQ (Temporary Storage Queues). Documenting how data flows from Step 1 to Step 50 manually is a recipe for data loss.

Modernizing Legacy UI is often the first step in unlocking these trapped workflows.

The High Cost of Manual Discovery#

Industry experts recommend a "documentation-first" approach to migration, but the math rarely adds up for manual efforts. If a single complex screen takes 40 hours to document—including field-level validations, error handling, and navigation logic—a 50-step workflow represents 2,000 man-hours.

By using Replay, organizations can bypass the "discovery phase" that typically kills large-scale modernization projects. Instead of hiring consultants to interview users for six months, you record the 50-step workflow once.

Understanding Visual Reverse Engineering#

Visual Reverse Engineering is the process of using computer vision and AI to reconstruct application logic and UI components directly from user interface recordings, bypassing the need for incomplete or missing source code documentation.

When telon mainframe screens documenting is performed via Replay, the platform captures every PFK (Program Function Key) press, every "Clear" screen, and every data entry point. It doesn't just take a screenshot; it understands that a specific coordinate on a 3270 terminal represents a "Policy Number" field with a specific validation rule.

From Green Screen to React: The Transformation#

Once Replay captures the Telon workflow, it translates the visual elements into a modern Design System. This isn't just a "skin" over the mainframe; it's a full extraction of the component architecture.

For example, a Telon "Update" screen with 50 fields is converted into a structured TypeScript interface and a React functional component.

typescript
// Example of an extracted Telon Screen Component structure
interface PolicyUpdateProps {
  policyNumber: string;
  effectiveDate: string;
  coverageLimits: number[];
  onCommit: (data: PolicyData) => void;
  onNavigate: (nextScreen: string) => void;
}

const PolicyUpdateScreen: React.FC<PolicyUpdateProps> = ({ 
  policyNumber, 
  onCommit 
}) => {
  // Replay automatically identifies field validations from the recording
  const [formData, setFormData] = useState({ policyNumber });

  return (
    <div className="legacy-container">
      <Header title="Policy Maintenance - Step 12 of 50" />
      <Input 
        label="Policy Number" 
        value={formData.policyNumber}
        readOnly 
      />
      {/* Automated layout generation based on Telon coordinates */}
      <Button variant="primary" onClick={() => onCommit(formData)}>
        F3 - Save & Continue
      </Button>
    </div>
  );
};

Documenting 50-Step Workflows: A Strategic Approach#

When dealing with massive workflows, telon mainframe screens documenting requires a hierarchical approach. You cannot simply look at 50 screens in isolation. You must understand the "Flow."

1. The Macro View (The Flow)#

Replay’s "Flows" feature allows architects to see the entire 50-step journey as a visual graph. This identifies redundant steps—often, legacy workflows have "buffer" screens that were only necessary due to 1980s memory constraints.

2. The Micro View (The Blueprint)#

Each screen is broken down into its "Blueprint." This is where the specific Telon attributes (like

or ) are converted into modern UI states (like or ).

3. The Data View (The Library)#

Replay extracts a consistent Design System from the recording. If the same "Customer Search" pattern appears in 10 of the 50 steps, Replay identifies it as a reusable component, preventing the creation of duplicate code.

Building a Design System from Legacy is essential for maintaining consistency in the new environment.

The Technical Reality of Telon Modernization#

According to Replay’s analysis, the biggest risk in telon mainframe screens documenting is missing the "Implicit Logic." This is logic that isn't written in COBOL but is enforced by the Telon screen definition itself—such as a field that only accepts numeric input or a screen that automatically submits when the last field is filled (the "Auto-Skip" feature).

Manual documentation almost always misses these nuances. Replay’s AI Automation Suite detects these patterns by analyzing the user's interaction timing and input behavior.

tsx
// Replay captures implicit Telon logic like Auto-Skip and Field Masking
import { useLegacyValidation } from '@replay-build/runtime';

export const TelonClaimScreen = () => {
  const { validateNumeric, handleAutoSkip } = useLegacyValidation();

  return (
    <form>
      <input 
        type="text" 
        onChange={(e) => {
          if (validateNumeric(e.target.value)) {
            // Logic extracted from Telon screen behavior
            handleAutoSkip(e.target.value, 8, 'NEXT_FIELD_ID');
          }
        }}
        maxLength={8}
      />
    </form>
  );
};

Industry Applications: Why it Matters Now#

Financial Services#

In banking, 50-step workflows are common in "Know Your Customer" (KYC) and loan origination. Missing a single validation step during telon mainframe screens documenting can lead to multi-million dollar regulatory fines. Replay provides a HIPAA-ready and SOC2 compliant environment to document these flows without exposing PII (Personally Identifiable Information).

Government and Public Sector#

Many state agencies still run on Telon-based unemployment or tax systems. With the "Silver Tsunami" of retiring COBOL programmers, the window for manual documentation is closing. Replay allows these agencies to record their current subject matter experts (SMEs) performing their daily tasks, effectively "downloading" the system's logic before the experts leave.

Insurance#

Claims processing in insurance is the poster child for complex Telon workflows. A single claim might touch 50 different screens across three different CICS regions. Replay’s ability to track these flows across region boundaries is a game-changer for insurance architects.

Overcoming the "Documentation Debt"#

The $3.6 trillion technical debt problem isn't just about old code; it's about the lack of understanding of that code. When you spend 18 months on a rewrite, 12 of those months are typically spent just trying to figure out what the current system does.

By shifting to a Visual Reverse Engineering model, you reduce the discovery phase by 90%. You move from "guessing" what the Telon screen does to "knowing" exactly how it behaves.

Video-to-code is the process of recording a user session and automatically generating the corresponding frontend code, state logic, and architectural documentation. This is the core engine of Replay, and it is the only way to handle the scale of 50-step mainframe workflows.

The Replay Workflow for Telon Screens#

1. •Record: A user performs the 50-step workflow in their standard terminal emulator.
2. •Analyze: Replay’s AI identifies every field, label, and navigation trigger.
3. •Document: The platform generates a "Blueprint" for every screen and a "Flow" for the entire sequence.
4. •Export: Architects export documented React components and a full Design System.

This process transforms telon mainframe screens documenting from a chore into a strategic asset. You aren't just creating a manual; you are creating the foundation of your new application.

Explore Replay Features

Frequently Asked Questions#

How does Replay handle sensitive data during the recording of Telon screens?#

Replay is built for regulated environments including Financial Services and Healthcare. It features automated PII masking and is SOC2 and HIPAA-ready. For maximum security, Replay can be deployed On-Premise, ensuring that sensitive mainframe data never leaves your secure network during the documentation process.

Can Replay document workflows that span across multiple mainframe regions or applications?#

Yes. Replay captures the entire user journey regardless of the underlying backend transitions. If a 50-step workflow moves from a Telon-based CICS application to a native IMS screen and then to a web portal, Replay documents the entire end-to-end "Flow" as a single cohesive architectural map.

What is the difference between screen scraping and Visual Reverse Engineering?#

Screen scraping simply captures text from a terminal to display it elsewhere. Visual Reverse Engineering, as performed by Replay, reconstructs the underlying component logic, data structures, and state management. It produces clean, documented React code and a reusable Design System, rather than just a visual overlay.

Does Replay require access to the original Telon source code or macros?#

No. One of the primary advantages of Replay is that it works entirely from the visual output and user interaction. This is critical for the 67% of legacy systems that have missing or corrupted source documentation. While source code can be used to augment the findings, it is not a prerequisite for telon mainframe screens documenting.

How does the 70% time savings manifest in a real-world project?#

In a traditional 18-month rewrite, roughly 6 months are spent on discovery and documentation. Replay reduces this 6-month phase to approximately 2-3 weeks. Furthermore, because the output is production-ready React code rather than static text, the development phase is also significantly accelerated.

Ready to modernize without rewriting? Book a pilot with Replay